1. Field of the Invention
The invention relates to a nozzle for injection molding machines for synthetic plastic materials. The nozzle comprises a shaft containing plastic material and is provided with a tip and a flow channel divided into at least two partial channels prior to reaching the tip.
2. Description of the Prior Art
In a known nozzle the shaft consists of a rod shape pointed as a whole and provided with an axial bore serving as the flow channel for the plastic material, said bore branching out prior to reaching the tip into two laterally angled bores.
The known nozzle has several important disadvantages. Its essential disadvantage consists of that the division of the flow channel into two branching and in particular laterally angled partial channels results in two changes in the direction of flow of the plastic material during the injection process, which in turn leads to permanent alterations of the material structure. After the recombination of the plastic mass the known memory characteristic of the material may be only partially reversed or not at all. The results of these permanent structural changes are lasting quality defects of the finished injection molded part, in particular in relation to mechanical strength. In addition, the known nozzle presents a critical disadvantage affecting its industrial use. The tip is a highly stressed part of the nozzle and experiences a high rate of wear necessitating frequent replacements, especially in cases where reinforced plastic materials, i.e. those containing glass fibers, are injected. With the known nozzles such a replacement requires the changing of the entire nozzle shaft, involving a considerable expenditure of material and of labor, as the replacement of the shaft makes it necessary to dismantle the heating jacket surrounding the shaft.